bradshaw



M51121! 3, 1936. I A, B A 2,032,974-

LOCK

Filed June 10, 1935 F/GJZ a g INVENTOR ATTO RN EY Patented Mar. 3, 1936UNITED STATES PATENT OFFICE LOCK Application June 10, 1935, SerialNo.25,894

1 Claim.

This invention relates to locks of the character employingspring-pressed slidable tumblers actuated into releasing position by theinsertion of a key in a keyway of a plug of the lock, and has for theprimary object the provision of antipicking means which will practicallyeliminate the possibility of picking the tumblers and if shifted by thepicking instrument will efi'ect locking of the plug to its cylinder sothat should even the tumblers be successfully actuated or picked theplug will remain locked to the cylinder of the lock.

With these and other objects in view, this invention consists in certainnovel features of construction, combination and arrangement of parts tobe hereinafter more fully described and claimed.

For a complete understanding of my invention, reference is to be had tothe following description and accompanying drawing, in which Figure 1 isan end View illustrating a keyway in the plug of a lock.

Figure 2 is a side elevation illustrating the cylinder of the lock withthe plug therein and showing a slot in the cylinder for the reception ofthe anti-picking means.

Figure 3 is a view similar to Figure 2, showing another side of thecylinder with a slot for the reception of the spring-pressed tumblers ofthe plug.

Figure 4 is a sectional view taken on the line 4-4 of Figure 3 showingthe anti-picking means.

Figure 5 is a sectional view taken on the line 5--5 of Figure 3 showingthe spring-pressed slidable tumblers securing the plug against rotationin the cylinder of the lock.

Figure 6 is a sectional view taken on the line 66 of Figure 4.

Figure '7 is a sectional view taken on the line 'l-l of Figure 5.

Figure 8 is a detail view showing the construction and the arrangementof the anti-picking means.

Figure 9 is a detail sectional View showing associated tumblers.

Figure 10 is a plan view illustrating one of the tumblers.

Figure 11 is a sectional view taken on the line ll-|I of Figure 10.

Figure 12 is a plan view illustrating the key for effecting operation ofthe anti-picking means and the tumblers to free the plug from thecylinder of the lock.

Referring in detail to the drawing, the numeral l indicates acylinder ofa lock provided with pairs of oppositely arranged slots 2 and 3.Rotatably mounted in the cylinder is a plug 4 having a flange 5 at oneend to abut one end of the cylinder. The plug 4 is provided with akeyway 6 opening outwardly through the flanged end of the plug. Formedin the plug and communicative with the keyway is a chamber 1 whichslidably receives pairs of tumblers 8 each having a key slot 9. Thetumblers of each pair are 10 urged in opposite directions by a coilspring Ill bearing against shoulders or ribs ll formed on said tumblers.The tumblers of each pair on their opposing faces are grooved to receivethe ribs I l with the springs l0 confined in the grooves 5 between theshoulders. The springs l0 act to urge the tumblers apart and into theslot 2 of the cylinder thereby securing the plug to the cylinder againstrotation or removal therefrom.

The plug at opposite sides of the keyway is 20 equipped with chambers l2communicative with the keyway and arranged laterally of each other. Thechambers also open outwardly through the periphery of the plug tocommunicate with the slot 3 of the cylinder. Guard elements l3 are 25slidably mounted in the chambers I2 and are provided with pointedportions I4 adapted to normally traverse the keyway and engage innotches l5 formed in the walls of the keyway by the action of springsl6. One of the guard ele- 30 ments is arranged adjacent the mouth of thekeyway while the other guard element is between the guard elementlocated adjacent the mouth and the tumbler. The successful operation ofthe guard and the tumblers depends upon a key 35 ll, as shown in Figure12. One portion of the bit of the key is designed to slide the pairs oftumblers out of the slot 2 of the cylinder when the key is shoved intothe keyway, said portion of the bit of the key when striking the guardsi3 40 causing said guards to slide outwardly into the slots 3 of thecylinder. A portion of the bit of the key adjacent the handle isprovided with notches to permit the guards to enter and there- 5 bypermit the springs Hi to position the guards out of the slots 3 of thecylinder. The key completely pushed into the keyway brings about theforegoing described operation of the tumblers and the guards and freesthe plug of the cylinder. Should an attempt be made, by the employmentof an instrument other than the regular key, to actuate the tumblers,the guards will check the movement of the instrument into the keyway forthe actuation of the tumblers. However, should a person be successful inpassing the guard with the instrument to reach the tumblers said guardswill be forced outwardly into the slots 3 of the cylinder and therebystill maintain the plug locked to the cylinder even if the tumblers weresuccessfully picked or actuated to bring about disengagement of thetumblers from the slot 2. Therefore, it will be seen from the foregoingdescription and the accompanying drawing that a practical means has beenprovided which will effectively prevent picking of the tumblers and evenif the tumblers are reached for successful operation, the anti-pickingmeans will efiectively secure the plug to the cylinder.

The guards when extended into the slots 3 and in contact with oppositewalls of said slots so position the plug in the cylinder that the endsof the tumblers will be positioned in spaced relation to the walls ofthe slot 2.

Having described the invention, I claim:

In a lock, 2, cylinder having guard and tumbler slots, a plug mounted insaid cylinder for rotation and having a keyway and tumbler and guardchambers, spring actuated tumblers mounted in said tumbler chamber andnormally entering the tumbler slots of the cylinder, and. having keyslots to receive a key in the keyway for moving the tumblers out of thetumbler slots of the cylinder, said guard chambers being arrangedlaterally of each other and at opposite sides of the keyway, guardelements slidable in the guard chambers and having pointed portionsadapted to traverse the keyway, said plug having notches in walls of thekeyway to receive the pointed ends of the guards, and springs secured tothe plug and engaging the guards to normally position the pointed endsthereof in the notches and thereby close the keyway between the mouth ofthe latter and the tumblers. 20

AUSTIN A. BRADSHAW.

